Research On Application Of Municipal Solide Waste Combustion Residues For Freeway Pavement Base

Along with the rapid development of the national economy and urbanization, the production of municipal solid waste (MSW) increases quickly. There are still huge amount of combustion residues, even though using the advanced incineration technology. It will impropriate plenty of land and landfill to dispose these residues, and this can result in environmental destruction. Meanwhile, the construction of freeway is always limited by the sources of aggregates in many areas in China. According to this situation, the first time research on applying combustion residues to freeway pavement base in China was conducted in this paper.In this paper, the physical and chemical properties of combustion residues were sdutied on. Based on this, using residues to replacing part of macadam to making semi-rigid base materials were carried out, and it was also conducted about the performances and the environment impact of the new masterials. Besides, the contrast tests with the traditional materials were also designed to analyse the impacts of residues content to the performances of the new materials.The results show that the maximum unconfined compressive strength of lime-fly ash stabilized residues-macadam can reach to 1.03MPa with the residues content of 77.5%, and this value can meet the requirement of freeway pavement base. However, if the content of residues was very high, the strength will decrease obviously. The maximum shrinkage coefficient of this new material was 67.2μ/%. If the content of lime and fly ash decreases by 2.5%, the shrinkage coefficient of this new material will decrease by 3.88%.Comparing to the traditional cement stabilized macadam, the unconfined compressive strength of cement stabilized residues-macadam decreases by 1.16% with 24% combustion residues content. And the water lost value at the tenth day can reach to the 81.9% of the final water lost value. With the cement content of 4.0% and 4.5%, the shrinkage coefficients of cement stabilized residues-macadam decrease by 9.2% and 11.5% respectively. The results of water stability test, dry-wet cycle test and freeze-thaw cycle test show that, for this new material, the properties of resisting water damage and freeze-thaw cycle are impacted seriously by, and this paper suggests that the health preserving age of this new material should be increased.The surface of residues is coarser than macadam, and there are a lot of micro particles at the residue's surface. The amount of reaction products of cement at the residues surface is larger than at the macadam surface. The leaching results show that the application of residues is safe.The contents of this paper provide evidence for using the residues to freeway pavement base, and the new materials can use in freeway and first class highway pavement base.